Costa Rica · Guanacaste
Catalina Islands
Dry-season Pacific diving often brings easier surface conditions and mantas.
The Catalinas off Costa Rica's Guanacaste coast are seasonal manta and bull-shark country — volcanic pinnacles in nutrient-rich Pacific water, accessed by 30–45 min boat from Playas del Coco.
Good season
May–November is peak (rainy season but best for big animals). December–April is calmer but mantas less reliable.
Trip duration
3–5 nights from the Guanacaste coast.
Dive style
Pinnacle and reef diving with moderate-to-strong current; some surge.
Dive level
Advanced recommended.
Reef health
What you’ll actually findThis reef is under heat stress right now and has thinned over the last decade. Plan a trip this year rather than next.
Coral reef health
How is this calculated?On current trend, no live coral by ~2078. Losing about 0.5% cover per year — roughly 54 years of reef left to see if nothing changes.
Heat stress right now
Reefs at this level can start losing colour within weeks.
NOAA Coral Reef Watch · updated May 2026 · 0.9 °C-week heat dose
What to expect on a dive
Bull sharks, mobulas, rays. Eastern Pacific reef ecology is naturally low-coral compared to Indo-Pacific reefs.
Sources, methodology, and the raw numbers
Raw observed numbers
- Coral cover: 27% (survey Sep 2024, Eastern Tropical Pacific reef survey)
- Bleached: 12%
- Recent mortality: 4%
- Eastern Tropical Pacific — observed condition reflects the thinning regional pattern.
Raw thermal numbers
- NOAA CRW alert level: Warning
- Degree Heating Weeks: 0.9 °C-wk
- SST anomaly: +1.4 °C
How we summarise this
Observed coral cover, bleaching, and mortality come from named in-situ surveys with a stated date and method — they describe one snapshot of one reef and do not extrapolate to neighbouring sites. Current thermal stress is satellite-derived from NOAA Coral Reef Watch at ~5 km resolution; it indicates risk, not observed coral damage. We deliberately separate observed condition, current thermal stress, and projection — and we never publish a projection without a documented model and uncertainty.
Sources
- International Coral Reef Initiative — ICRI Secretariat
- NOAA Coral Reef Watch — U.S. National Oceanic and Atmospheric Administration
- AIMS Long-Term Monitoring Program — Australian Institute of Marine Science
- Global Coral Reef Monitoring Network — GCRMN / ICRI
- Atlantic and Gulf Rapid Reef Assessment — AGRRA Program / Perry Institute for Marine Science
- NOAA National Coral Reef Monitoring Program — NOAA Coral Reef Conservation Program
- Reef Check — Reef Check Foundation
- NOAA CoastWatch / OceanWatch — NOAA NESDIS / STAR
- Allen Coral Atlas — Arizona State University Center for Global Discovery and Conservation Science
- Great Barrier Reef Marine Park Authority — Australian Government
- Reef Life Survey — Reef Life Survey Foundation
- NASA PO.DAAC — NASA Jet Propulsion Laboratory / Caltech
- Copernicus Marine Service — Mercator Ocean International for the European Union
- NASA Ocean Color (OB.DAAC) — NASA Goddard Space Flight Center / Ocean Biology Processing Group
- Argo float network — International Argo Program / UCSD
- CoralWatch — University of Queensland
- IMOS / AODN — Integrated Marine Observing System / Australian Ocean Data Network
- WRI Reefs at Risk Revisited — World Resources Institute
- Ocean Health Index — OHI partnership (Conservation International + UCSB + NCEAS)
- IPCC Special Report on the Ocean and Cryosphere (SROCC) — Intergovernmental Panel on Climate Change
- GOA-ON — Global Ocean Acidification Observing Network — GOA-ON Secretariat + IOC-UNESCO
- HAEDAT — Harmful Algae Event Database — IOC-UNESCO Intergovernmental Panel on Harmful Algal Blooms
- NCEI Marine Microplastics — NOAA National Centers for Environmental Information
Reef condition changes year to year. If you visit, consider supporting responsible-travel and conservation operators on the ground.
Pressure on this reef
Protection · fishing · what you can doProtected-area status
Strict MPAInside a strict marine protected area with active enforcement.
Fishing pressure
Moderate fishing pressureDominant pressures
- sargassum influx
- SCTLD
- tourism overdevelopment
3 Green Fins-verified operators known at this location.
What you can do
Mesoamerican Reef is partially protected by national parks. Sargassum and SCTLD are the dominant pressures. Support operators participating in coral nurseries.
Protection status sourced from Protected Planet / WDPA and refined with Marine Protection Atlas. Fishing pressure proxy is Global Fishing Watch AIS data. See the methodology for what these sources can and can’t prove.
Dive sites here
1 curated
Gear
What to bringSite-specific add-ons
Some dive sites here call for extra gear. Check the individual site page for full context.
- Temperate wetsuit — Upwellings in manta season push water below 20°C with sharp thermoclines — a 5mm full suit plus hood is standard from December through March. · La Pared (The Wall)
- SMB + reel — Drift profiles along the wall regularly end in blue-water ascents; surface marker buoy is required for boat pickup in current. · La Pared (The Wall)
What divers say
“Pacific Costa Rica isn't the prettiest water, but the manta odds in August are absurd.”